diff --git a/.appveyor_support/environments/requirements_py36.txt b/.appveyor_support/environments/requirements_py36.txt
index 4953d79..d3d3a37 100644
--- a/.appveyor_support/environments/requirements_py36.txt
+++ b/.appveyor_support/environments/requirements_py36.txt
@@ -38,7 +38,7 @@ kiwisolver==1.1.0
 markupsafe==1.1.1
 matplotlib==3.1.0
 mccabe==0.6.1
-mistune==0.8.4
+mistune==2.0.3
 more-itertools==7.0.0
 nbconvert==5.5.0
 nbformat==4.4.0